1. Field of the Invention
The present invention relates to a toy rifle (air soft rifle/BB-rifle) and more particularly, to a toy riffle backlash vibration structure that allows adjustment of the backlash vibration from zero to the maximum level.
2. Description of the Related Art
To simulation of a real automatic rifle, a toy rifle (air soft rifle/BB-rifle) may be provided with a backlash vibration structure. Taiwan Patent Publication No. 200708712 discloses a similar design. However, this design is still not satisfactory in function.
FIG. 1 illustrates a backlash vibration structure a′ installed in a toy riffle. As illustrated, the backlash vibration structure a′ is arranged at the rear side in axial alignment with the piston 10 in the piston-cylinder mechanism b′, comprising a receiver extension 20, a weight 30, a reaction spring 40, and a buttcap spacer 50 The receiver extension 20 is connected to the rear side of the lower receiver c′ that accommodates the piston-cylinder mechanism b′. The weight 30 and the reaction spring 40 are mounted inside the receiver extension 20. The reaction spring 40 is connected between the weight 30 and the buttcap spacer 50. The piston 101 has its rear side mounted with a piston spring 101. The piston spring 101 has its one end received in the piston 10, and its other end stopped against an inside wall of the lower receiver c′. Further, a connection rod 60 is movably inserted through the lower receiver c′ and connected between the piston spring 101 and the weight 30. The toy riffle further comprises a transmission mechanism d′, a trigger c′ and a bullet pusher f′. When pressed the trigger e′, the transmission mechanism d′is forced to move the piston-cylinder mechanism b′, causing the bullet pusher f′ to push the bullet into the firing position for striking by (the firing pin of) the piston 10. During movement of the transmission mechanism d′, the piston 10 is moved backwards, and the connection rod 60 is moved with the piston 10 to force the weight 30 against the reaction spring 40 (see FIG. 2). When over the compression limit of the reaction spring 40, the reaction spring 40 forces the weight 39 forwards, and the piston 10 is moved forwards in a rush to shoot the bullet (see also FIG. 1). During forward movement of the weight 30, a reactive force is produced, causing a backlash vibration.
According to the aforesaid design, the connection rod 60 is connected between the piston spring 101 and the weight 30 and has its front end suspending in the piston 10, the inside wall of the piston 10 will strike the front end of the connection rod 60 during backward movement of the piston 10, and the front end of the connection rod 60 will strike the inside wall of the piston 10 during forward movement of the weight 30. Therefore, the piston 10 wears quickly with use. Further, the pressure of the backlash is determined subject to the weight of the weight 30 and the spring force of the reaction spring 40 and the piston spring 101. However, because the weight of the weight 30 is fixed, and the spring force of the reaction spring 40 and the piston spring 101 will be gradually reducing after a long use. In consequence, the backlash vibration will become small and not adjustable after a long use of the toy riffle. Therefore, an improvement in this regard is necessary.